Imaging and safety system and method for an industrial machine

ABSTRACT

An imaging system, safety system or combined imaging and safety system includes a light transmitter and a corresponding receiver. Image data relating to a machine tool and/or workpiece is derived and processed to determine information regarding the tool and/or tool position and/or extent of work carried out on the workpiece. A screen, such as a shadow screen, can be used to form an image of a profile of the tool tip and end of the workpiece. Tool tip position and extent of work on the workpiece can be derived from the image. Certain aspects are directed to a safety system application for halting a machine or tool when a light beam is interrupted, and can provide progressive muting of beam interruption detection, such as by systematically disregarding or muting signals from rows of receiver array elements as the beam passes through a mute point ahead of a tool.

RELATED PATENT DOCUMENTS

This patent document is a continuation under 35 U.S.C. §120 of U.S.patent application Ser. No. 12/780,070 filed on May 14, 2010 (U.S. Pat.No. 8,692,877); which is further a continuation of U.S. patentapplication Ser. No. 11/993,200 filed on Dec. 19, 2007 (abandoned);which is the national stage filing under 35 U.S.C. §371 of InternationalApplication No. PCT/AU2006/000859 filed on Jun. 20, 2006; which claimsforeign priority benefit under 35 U.S.C. §119/365 of Australian PatentApplication No. 2005903214 filed on Jun. 20, 2005, each of which(including any Appendices or other materials related thereto) is fullyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention is generally directed to a light beam system andmethod applicable to an industrial machine. In particular, the presentinvention relates to a light beam safety system and also to a system forautomatically determining the status of material being worked by theindustrial machine, such as industrial presses, press brakes orguillotines, and also industrial lathes, such as CNC lathes. Althoughthe present invention will now be described with respect to press brakesfor ease of understanding, it is to be appreciated that otherapplications of the present invention, such as on milling and turningmachines, CNC machines and presses in general, are also envisaged tofall within the scope and ambit of the present invention.

BACKGROUND OF THE INVENTION

The Applicant has previously developed safety systems for industrialpresses utilizing one or more light sources, each emitting a singlecontinuous planar laser beam having a generally constant lateral width,and a light receiver for each beam. A single beam safety system isdescribed in Australian patent number 738619, and a multiple beam systemis described in Australian patent application number 2003215410, both ofwhich are incorporated herein by reference. In such systems, both thelight source(s) and the light receiver(s) are mounted on the moveablesection of the industrial press. In the case of a press brake, the lightsource(s) and light receivers are mounted for movement with the moveabletool, and the tool (and the laser and light receivers mounted thereon)move relative to a stationary anvil or die section supporting a piece ofsheet material to be bent by the tool. An example of such a safetysystem is described in International Patent Application No.PCT/AU00/00420, details of which are incorporated herein by reference.Especially when bending sheet materials using press brakes, the accuracyof the bending angle which is obtained depends, firstly, on thecharacteristics of the sheet, such as its thickness, which may vary fromone sheet to another, and its physical and geometrical characteristics,on which the elastic return of the sheets depends. Furthermore,characteristics of the press itself, especially tolerance in theconstruction of the machine and tooling and wear on the tools, and alsodefamations appearing in the press at the instance of bending can alsoplay a part in the bending angle.

Arrangements have previously been proposed to permit instantaneousautomatic control of the bending operation in respect of the piece ofmaterial to be bent, so as to obtain, automatically and exactly, thedesired bending angle of the material, while avoiding any manualintervention before and during the bending. Such automatic systemsalleviate the need for manual adjustment and/or observation.

One such prior art automatic system is disclosed in U.S. Pat. No.4,564,765, which proposes an opto-electronic measuring method and anapparatus for measuring material defamations in processing machines,particularly of the bending angle in free-bending die presses. Thisarrangement proposed one or two light spots produced on the deformingsurface of the material, such as the bending side of a sheet metalplate, using a laser, infra-red emitting diode or the like, directed atan acute angle to the underside of the sheet material to be bent. Thedistance covered by the light spot, and the distance of the light spotsfrom one another, respectively, are received by means of a photodetector, e.g., a diode line camera, which is set up at a distance andapproximately perpendicular to the light spot or spots, and the measuredvalues are compared with the index value in a microprocessor, e.g., bymeans of the control of the emotion depth of the bending die. At leastone light source is arranged to strike the underside of the sheet metalplate at an angle relative to the bending axis. If the sheet metal plateis bent, the light spot appears to travel along the underside of thematerial. A sensor detects the extent of travel of the light spot andthe resulting bending angle of the material can be determined form thedisplacement of the light spot relative to its starting position.However, such a system is limited in application to the bending of sheetmaterial, and the accuracy of the determined angle of bend decreaseswith increasing bend angle due to the apparent travel of the light spotdecreasing as the material is bent.

An alternative system has previously been proposed in U.S. Pat. No.4,772,801. This patent discloses a light beam device for automaticallycontrolling the bending operation when bending the press brake. Thedevice includes an emitter mounted on one side of the press adapted toproduce a large diameter light beam directed parallel to the bendingaxis of the work piece to be bent, i.e., along the length of the workpiece to be bent, and the receiver including a box including a screendrilled with a plurality of holes arranged to form a plurality of lightbeams of small diameters. The box comprises a deflecting means intendedto deflect the light beams onto a system of photo diodes arranged on theaxis of rotation of a rotating motor and angle encoder. A microcoordinator is connected to the photo diodes and to the angle encoder,and permits the determination of the instantaneous bending angle of thework piece, and also makes possible determination of the speed ofdescent of the tool. However, aforesaid arrangement has limitedapplication in needing to be attached to the lower table of a press andrequires relatively complex moving parts and having a prism mounted forrotation about the axis of the image analyser. Furthermore, the accuracyof flexibility of measurement of the bend angle of the material islimited by the number of holes, and the separation distance betweenadjacent holes in a radial direction of the encoder from the axis ofrotation, such that error in the determination of the bend angle can besignificant.

An alternative system is disclosed in U.S. Pat. No. 4,550,586. Thispatent discloses a device employing a number of detectors mounted at alevel of the upper surface of the die of an industrial press. Thepurpose of the detectors is to signal to a numerical control the momenta portion of a sheet of material to be bent begins to rise from theupper surface of the die, i.e., during bending. The device allowsautomatic determination of the thickness of the sheet and the area wherethe bend is to be located during the course of forming a bend. Thethickness of the sheet can then be used by the numerical control systemto correct the travel of the tool, without interrupting the formingcycle, in such a way as to obtain, with high precision, the requiredbend angle of the sheet material. However, with the detectors lyinglevel with and adjacent to the upper surface of the die, such detectorsare prone to damage or being accidentally obscured during bendingoperations and impeding and slowing down the loading and unloading ofwork pieces, e.g., sheets of metal.

Many industrial machines, including press brakes, utilise a safety lightbeam system that will stop the machine operating if the safety beam isinterrupted prior to a mute point, but will disable this stoppingfunction after the mute point. Utilising machine operating speed up tothe mute point is therefore important for productivity, whilst stillneeding to be able to stop the machine within sufficient travel distanceto prevent injury to an operator. Thus, many machines are operated athigh speed up to the mute point in order to maximise efficiency andproductivity, and at a slower operating speed after the mute point.

For many safety systems that utilise either a single or multiple beams,operation is much the same. Interruption of one or more beams stops themachine. However, for broad or multi beam applications, i.e., lightbeams having a broad 2 dimensional cross section (depth and height) inthe order of centimeters or multiple beams effectively providing a broadsafety zone, the tool tip may be several millimeters or centimeters awayfrom the mute point when the first portion of the beam ahead of the tooltip reaches the mute point. In such scenarios, the machine would switchto slow speed because the broad beam has reached the mute point. Thismay lead to lost efficiency or productivity.

It would therefore be beneficial to provide a light beam safety systemfor an industrial machine that could recognise that part of the lightbeam had reached or passed the mute point and determine the requiredstopping distance.

With the aforementioned in view, it is one object of the presentinvention to provide a device for determining the progress of working ofa selected piece of material whilst alleviating one or more of theproblems of the aforementioned prior art.

It is a subordinate object of the present invention to provide animaging device for determining an angle of bend of sheet material in anindustrial press which allows constant determination of the angle ofbend.

A further object of the present invention is to provide a safety beamsystem for a press brake which provides an adaptable broad beamprotection zone to help maintain efficiency and productivity.

SUMMARY OF THE INVENTION

With the above mentioned in mind, one form of the present inventionprovides an imaging system for an industrial machine including at leastone light transmitter for mounting to a first portion of the industrialmachine, said at least one transmitter including means to transmit asubstantially collimated beam of light to a receiver, said receiverincluding at least one pixel matrix arranged to receive at least aportion of said beam, said receiver including output means to outputimage data, and an image processing means arranged to receive andprocess said output image data, wherein, in use, said receiver outputsto the image processing means image data relating to a pattern of saidbeam attenuated by said work piece and the remaining portion of saidbeam, and wherein said image processing means determines the extent ofwork carried out on said work piece by said tool based on said imagedata.

Thus, advantageously, the present invention permits determination of theextent of work carried out on a work piece by an industrial machinewhilst alleviating the need for manual intervention before and/or duringworking of the work piece.

Another form of the present invention provides an imaging system forautomatically determining an extent of work carried out on a work pieceby a tool of an industrial machine, said system including a lighttransmitter for mounting to a first portion of the industrial machine,said transmitter including:

at least one light source and means to transmit a substantiallycollimated beam of said light to a receiver;

a receiver for mounting to a second portion of the industrial machine,said receiver including an image information capture means and acaptured image information output means; and

an image processing means arranged to receive and to process said outputcaptured image information into image data;

wherein said system is arranged such that said work piece, whenilluminated by said beam, attenuates a portion of said beam transmittedto said image capture means, said receiver being arranged to output tothe image processing means captured image information relating to theportion of said beam attenuated by said work piece and the remainingportion of said beam, and wherein said image processing means determinesthe extent of work carried out on said work piece by said tool to createimage data.

Thus, such an advantageous form of the present invention also permitsdetermination of the extent of work carried out on a work piece by anindustrial machine whilst alleviating need for manual interventionbefore and/or during the working of the work piece.

Another form of the present invention provides an imaging system for anindustrial machine, said system including a light transmitter includingmeans to transmit a substantially collimated beam of light to areceiver, said receiver including an image plane arranged to display animage formed by attenuation of at least a portion of the beam whenilluminating the work piece and/or tool interposing between thetransmitter and plane, image capture means arranged to interpret andconvert said image into image data, and image data processing meansarranged to determine from said image data an extent of work carried outon said work piece by said tool and/or a profile of said tool based onsaid image data.

Preferably, the light transmitter includes at least one light source,such as one or more laser diodes, and more preferably may include a lenssystem for focussing and/or collimating the beam(s). For example, thetransmitter may include a lens arrangement for spreading and focussinglight into one or more wide fan or planar (say horizontal) beams andthen a subsequent section to form the resultant beam into a broadX-section beam by spreading the fan or planar beam(s) into one or morebeams having substantial height and width in 2 dimensions e.g., 50 mm×50mm X-section.

Preferably the receiver includes one or more image screens for capturingor resolving the image. Thus the image plane may include one or morescreens, such as shadow screens. Alternatively or in addition, the imageplane may include one or more cameras for directly imaging the receivedportion of the beam. Such cameras would include the image capture means,and preferably may include the image processing means.

Preferably the image plane may include one shadow screen arranged toform a shadow image created by the pattern of light falling on saidscreen e.g., pattern formed by a combination of attenuated andun-attenuated light. It will be appreciated that the work piece and/ortool may completely attenuate a portion of the beam. That is, theycompletely block light illuminating them from reaching the image plane.

A further form of the present invention provides a combined safety andimaging system for an industrial machine, including at least one lighttransmitter including means to transmit at least one substantiallycollimated beam of light to a receiver, wherein, up to a mute point,said system is configured to provide at least a safety mode which haltsan operation of said machine when an object intersects at least one saidbeam, and from said mute point, said system is configured to provide atleast an imaging mode, wherein said receiver receives a pattern of lightcreated by attenuation of at least a portion of at least one said beamilluminating a work piece and/or tool interposing between thetransmitter and receiver, said system including image capture meansarranged to interpret and convert said pattern into image data, andimage data processing means arranged to determine from said image dataan extent of work carried out on said work piece by said tool and/or aprofile of said tool based on said image data.

Thus, as the tool of the machine, such as a tool of a press brake orlathe, commences an operational movement, the system may initially be insafety mode until a pre-determined mute point is reached. From the mutepoint, the system may change over to, or initiate, an imaging mode whichis utilised to determine the progress of work carried out on a workpiece (e.g., degree of bend of sheet metal) and/or to determine whethera tool is the correct tool (compared to a library of stored data) or isworking/positioned correctly. Preferably the safety system is switchedoff at the mute point and the imaging mode switched on. In this way,duplication of components may be minimised by utilising the sametransmitter(s) and/or receivers for both the safety system and imagingmodes.

The mute point is generally determined as the point at which the safetysystem is no longer practical or prescribed, usually due to the toolbeing sufficiently proximate to the work-piece that an object is highlyunlikely to be able to interpose between the tool and work-piece andtherefore the risk of injury to a user is extremely low or negligible.

Preferably, the industrial machine may be a press brake. However, whilsta press brake is a preferred form of industrial machine for applicationof the imaging system according to the present invention, other machinesare considered to fall within the scope and ambit of the presentinvention where a work piece is subject to working by a tool. Forexample, lathes such as CNC lathes, milling machines, industrialpresses, and other bending and forming machines. Furthermore, it will beappreciated that the present invention is applicable to machines forworking a variety of material such as metal or plastics.

Preferably, the receiver e.g., the image capture means, may include atleast one pixel matrix. One or more of said pixel matrices may be ofmegapixel resolution or any other suitable matrix size e.g., 640×480array of pixels. However, other array sizes of matrices may be utilised.For example, one or more charge coupled devices; (CCD) may be utilizedto form a pixel matrix. More preferably, multiple pixel matrixes may beutilized and, even more preferably, the received beam may be split intomultiple resultant beams each to be received by a separate pixel matrix.Thereby, preferably, redundancy may be designed into the system byproviding multiple receivers and/or multiple pixel matrixes in one ormore of the receivers.

Preferably, the image capture means may be a screen, preferably of atranslucent or semi-translucent material, such as a shadow screen,whereby image information may be captured following attenuation of partof the beam, and the image information thereafter processed into imagedata. Preferably, the receiver comprises one or more cameras which mayview the captured image information, e.g., image information on ascreen, and therefrom the image data may be determined.

Preferably, the transmitter and receiver may be mounted for travel witha moving portion of a press brake, such as a working tool with adown-stroke press brake. That is, an industrial press may for example bea press brake having a blade and an anvil moveable relative to eachother. A beam may be emitted immediately adjacent the leading edge ofthe blade. According to one possible arrangement, the beam may behorizontal and located so as to be transmitted between the blade and theanvil of the press brake.

The light transmitter may include an actual light source, e.g., a lasersource, or may be taken as a device at which point the light is actuallytransmitted from a light providing device, such as a lens assembly,towards the workpiece.

The transmitted beam may have a circular or polygonal cross section,provided the beam is capable of illuminating a suitable area at theimage capture means. Preferably, the cross section of the beam issufficiently large to illuminate a required number of pixels in thematrix.

The light emitter may preferably include a laser emitter, for example, alaser diode for emitting a laser beam, and a lens assembly for varyingthe configuration of the laser beam emitted by the laser diode. Multipleemitting means may be used, such as multiple laser diodes. Laser beamsemitted by such laser emitters, when focussed, may be typicallycircular/spot in cross section are typically circular in cross section.One or more lens assemblies may be utilized to convert a circular laserbeam into a beam having a larger circular cross section, for example,40-50 mm diameter, or alternatively, a polygonal cross section, e.g.,square or rectangular. A cross section of such beams is generally formedas an expanded and collimated beam of greater cross section than theoriginating light source, so as to provide a monitoring zone, e.g.,imaging zone, having a relatively broad diameter or width, therebyproviding a monitoring zone of cross section larger in two dimensionsthan a prior art spot or planar beam. The cross section of the beam(s)e.g., of a “block” laser, may be reduced or focussed to a smaller sizee.g., by a lens arrangement, prior to illuminating a receiver e.g.,pixel array, shadow screen or other receiving device. It should be notedthat some dispersion of the collimated beam may occur the further away apoint on the beam is from the emitter. This dispersion is howeverrelatively insignificant within the range of distances that the beammust be emitted over, typically between 2-12 meters.

Preferably, the system is used to illuminate an end of a sheet ofmaterial to be bent by a bending press. The material may be metal or,alternatively, or in combination, other material such as plastic.

The imaging system may be combined with a safety system for the machine.For example, the light emitter may be a laser emitting means and thereceiver may be a laser light receiving means both mountable on theblade of a press brake, and may move with the blade if that part is themoveable section of the press brake. Where an object close enough to theblade intersects the laser beam, the blade will stop or preventoperation or further operation of the press. The beam may be acontinuous planar laser beam having a generally constant lateral widthsuch that the beam can cover a relatively wide area when compared with aconventional point laser beam, whilst at the same time ensuring thatthere are no “spaces” through which an object can pass withoutdetection.

Alternatively, multiple planar laser beams may be envisaged, such as, avertical series of horizontal planar laser beams and/or vertical planarlaser beams aligned in a horizontal series. As the tool progressestowards the work piece, an object intersecting one or more of the beamswill stop or prevent operation of the machine. Preferably, when the toolreaches a mute point, the system changes over from a safety system tothe imaging system. Thereby, conveniently and advantageously, theimaging system according to one or more forms of the present inventioncan be utilized to also serve as a safety system for the machine. Thus,duplication of components may be avoided, and in addition, productivityof the machine may be increased due to the reduced reliance uponmultiple systems and respective data for those systems to be calculated.

In regard to bending of materials, e.g., metal sheet in a press brake,the imaging system may be used to image an end profile of the metalsheet being bent. As the tool progressively bends the metal sheet into aV shape in combination with the anvil or die, the imaging system may beutilized to determine the increasing or decreasing degree of bend in themetal sheet. The image processing means may determine the degree of bendby using a “line of best fit” algorithm calculated from the data derivedfrom the attenuated light falling on some of the pixels. Both the lightemitting means and the light receiving means may be respectively mountedon supports on opposing sides of the moveable section of the press. Thesupports may be respectively adjustable to allow the alignment andposition of the emitting and/or receiving means to be adjusted. Forexample, where the moveable section is a cutting blade or bending tool,blades of different heights can be used, and the position of theemitting means and receiving means will need to be adjusted.Alternatively, only the emitter means need be adjusted, the lightreceiving means remaining fixed.

Preferably the at least one beam is perpendicular to the relativedirection of travel of the tool with respect to the work-piece. Morepreferably, the at least one beam extends in advance of and parallel tothe working tool of a press brake, and more preferably one or more beamsincludes a planar laser beam, such as is disclosed in Australian patentnumber 738619.

A further form of the present invention includes a method of operating acombined safety and imaging system for an industrial machine, saidmachining having a tool and a work piece holding part arranged forrelative movement towards one another, said system including a safetydevice and an imaging device, the method including the steps of:

a) providing an safety mode including a transmitter for transmitting atleast one substantially collimated beam of light to a receiver;

b) up to a mute point, halting relative movement of the tool towards thework-piece when an object intersects at least one said beam;

c) at least from said mute point, the system providing an imaging modewhereby the extent of work carried out on said work piece and/or theprofile of the tool is determined.

Preferably the safety device is configured to act as the imaging devicefrom the mute point and configured to act as the safety device prior orup to said mute point. Thus the system helps to avoid redundancy orduplication of parts in providing a combined system whereby the safetyand imaging components may be commonised.

Preferably, the method further includes the step imaging at least theworking part of the tool during at least one calibration operating cyclewithout the work-piece in position, and thereby establishing calibrationimage data relating to the tool and machine such that subsequent workingoperations with the work-piece in place can be imaged and compared tothe calibration image data to thereby determine the extent of workcarried out on the work-piece from differences between the unworked andworked work-piece.

A further form of the present invention provides a method fordetermining an extent of work carried out on a work piece by a tool ofan industrial machine, including the steps of:

transmitting a collimated beam of light between a light transmitter anda light receiver,

illuminating at least a portion of said work piece with said transmittedlight, said work piece attenuating at least a portion of saidtransmitted light,

receiving said beam including said attenuated portion,

processing said image data to determine from said received beam theextent of work carried out on said work piece by said tool based on saidprocessed image data.

Preferably the receiver includes a pixel matrix, shadow screen and/orcamera.

Thereby, for example, the degree of bend of a sheet of metal by a toolof a press brake can be determined from e.g. the “shadow” of the workpiece and remaining portion of the beam as received by the pixel matrix.

The system and method may continuously image the work piece, andpreferably display a derived image or angle measurement to a user, inorder to help monitor in real time the extent of work carried out on thework piece. Thus, should a fault arise, or the work piece be incorrectlyworked, or for example, the wrong tool being selected for apredetermined application, this can be detected by the system.

A further aspect of the present invention provides a safety system forhalting operation of an industrial machine when at least one light beamis interrupted, the system including progressive muting of an effectiveprotection zone.

Progressive or systematic muting advantageously allows adaptation of theprotection zone and/or to allow for enhanced speed control of the tool.

Benefits of the system include, but are not limited to, recognition ofinterruptions in broad beam (block—rectangular, circular etc.) sectionbeams running parallel to and ahead of the tool tip. It will beappreciated that some of the beam may extend behind the tool tip toprovide additional protection from incursion entering from above thetool tip, monitoring stopping distance, monitoring press brake tool highand low speeds, and may be used to assist controlling press brakeoperating speeds, and can monitor mute point position.

Preferably the system may include at least one transmitter and at leastone corresponding receiver arranged to receive light transmitted fromsaid at least one receiver, the machine including first and secondportions arranged for relative closing movement during operation of themachine, wherein the system is arranged to restrict or halt furtherrelative closing movement of the first and second portions when anoperative portion of said transmitted light received is interrupted, andwherein said at least one receiver includes a plurality of receiverelements, wherein operation of selected said receiver elements aresystematically disregarded or muted.

Preferably the safety system may disregard or mute signals from rows ofreceiver elements. The system may include at least one array of pixelsproviding said receiver elements.

Preferably the at least one light beam may include a broad or block beamhaving a two dimensional cross section with a significant depth andthickness, for example on the order of centimeters, e.g., 60 mm×60 mm.

A further aspect of the present invention provides a method of operatinga safety system for an industrial machine, including the steps of;

a) Progressively muting portions of a protection zone for a moving toolof the machine.

Preferably the method may include progressively disregarding or mutingrows of receiver elements of a receiver.

It will be convenient to further describe the invention by reference tothe accompanying drawings which illustrate a possible arrangement of thepresent invention. Other arrangements of the invention are possible, andconsequently the particularity of the accompanying drawing is not to beunderstood as superseding the generality of the preceding description ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of an application of a particular embodiment of thepresent invention having a combined imaging system and safety system.

FIG. 2 shows an end view of a system according to an embodiment of thepresent invention utilizing a twin planar laser beam safety system.

FIG. 3 shows an end view of an embodiment of the imaging systemaccording to the present invention utilized in a press brake for bendingsheet metal.

FIG. 4 shows an embodiment of the present invention utilized for imagingthe degree of bend of sheet material by a press brake.

FIG. 5 shows a further embodiment of the present invention wherein anexpanded light source is divided into multiple planar laser beams.

FIG. 6 shows a perspective view of an embodiment of the presentinvention mounted to a press.

FIG. 7 shows a front view of an embodiment of the present inventionmounted to a press.

FIG. 8 shows a section view through line A-A of the embodiment shown inFIG. 7.

FIG. 9 shows a perspective view of a block laser safety and/or imagingsystem according to an embodiment of the present invention.

FIGS. 10a to 10d show successive stages during progressive muting of ablock laser according to an embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring initially to FIG. 1, this depicts a graph of velocity (y-axisin millimeter per second) of a tool of an industrial machine againstdisplacement (x-axis) of the tool. In particular, the graph depictedrelates to the working tool of a press brake. Section A of the graphshows acceleration of the tool. In this example, a downward stroke ofthe press is envisaged, though the same principle applies to upstrokingmachines. It will be appreciated that the present invention may also beapplicable to other industrial machines, such as lathes and millingmachines. Nominal high speed of the tool is reached (e.g., atapproximately 150 mms⁻¹), and thereafter plateaus out to a steadyvelocity shown as Section B. Section C of the graph shows decelerationof the tool to a pressing or crawl speed (e.g., to 10 mms⁻¹). In FIG. 1,the tool actually comes to a halt (velocity=zero) where the decelerationline (Section C) meets the displacement x-axis of the graph. In theexample discussed and shown, one or more of Sections A-C relate to asensing mode of the system, and therefore to safety related movements.During movement in Section C, the laser beam is turned on and an objectobstructing the beam is detected by the system which causes the tool tohalt thereby preventing injury to a user or object intersecting thebeam. That is, the system is in safety mode. At a mute point D where thedeceleration line of section C crosses the slow/pressing speed (e.g., 10mms⁻¹) velocity axis, the system changes over to an imaging modeaccording to one or more forms of the present invention, and the safetysensing mode may be switched off. Section E of the graph shows the toolagain accelerating up to pressing speed (Section G) for bending the workpiece, in this example, bending sheet metal. The point F shows the pointof contact of the tool with the material, and subsequently, thereafter,displacement occurs below the top level of the die. Thus, the sheetmaterial is bent, e.g., into a “V” shape, by the tool in pressing thematerial into the die.

FIG. 2 shows twin planar laser beams 1 a, 1 b used in a safety systemfor a press brake, such as are disclosed in Australian patentapplication number 2003215410, the contents of which are incorporatedherein by reference. The twin planar beams 1 a and 1 b are arranged todescend with, and ahead of, the tool 2 of the press. Interruption of oneor both of the beams 1 a and 1 b prior to a mute point 5 will cause thetool to halt descent. As the leading planar beam 1 b reaches the mutepoint it may be deactivated leaving only planar beam 1 a operative. Atthis stage, imaging of the degree of bend of the sheet material is notactivated. As the tool continues to descend, planar beam 1 a is switchedoff when it meets the mute point and the imaging system is switched on.

FIG. 3 shows an end view of an expanded light source 6, such as a“block”, i.e., broad cross section, laser beam used to illuminate theend of the work piece 3 and/or the tool 2. The use of an expanded lightsource enables a wider and higher imaging area to be covered comparedwith individual spot or planar beams. However, it will be appreciatedthat the broad section imaging area can be produced by multiple smallersection beams collimated such that the beams extend parallel with eachother and close together to form an equivalent broad beam. The beam canbe set so that the top of the beam detects the tip 7 of the tool at alltimes. That is, the block laser can travel with the tool in much thesame way that the safety laser beams travel with the tool. When thepress is activated, the block laser will descend with the tool anddetect the die from a distance of approximately 40 mm through to theclosed tool. The controller software utilized by the system will be suchthat the tool will not be permitted to physically touch the die unlessotherwise programmed.

Pixel array(s) allow(s) complex patterns or zones to be detected duringthe safety mode, significantly increasing the level of safety provided.Given the amount of processing required during high speed movement ofthe tool, only a portion of the pixel array(s) will preferably beutilised e.g., horizontal rows or vertical columns of pixels, orcombinations of both. For example, there can be a zone depending on thestopping distance of the machine, for example, 6 mm underneath and uparound the forward and rear face of the tool, that if obstructed, causesthe tool to halt. There can be a zone on the pixel matrix further awayfrom this initial zone that, if obstructed, triggers a deceleration downto a stop. In addition, there can be a further monitored zone beyond theaforementioned zones that only triggers slow speed if obstructed, and ifthe obstruction is taken away again full speed is resumed.

Profiles of machine tools and parts to be worked can be recognised bythe system, for example, comparing the image object with a library ofstored parts or tools. Thereby, protection zones and blanking zones canbe automatically adjusted to suit the tools and parts more easily. Thusthe top and bottom tool can be imaged to help ensure the top tool andbottom tool (anvil or die) meet correctly. Alternatively or in addition,the form of the part to be created can be stored to ensure that the partbeing worked takes the expected shape. Any deviation from the expectedpart shape or expected tool(s) can be detected by the system. The systemcan therefore adjust the protection areas to suit.

The use of the broad (block) beam allows the angle of depth of thematerial being worked to be measured on every working action e.g.,bending or machining. This enables the machine to incorporate anefficient and simplified measurement system for determining the bendangle or amount of machining whilst limiting capital costs.

Due to the potential arrangement of viewing the end of the material tobe worked, material planeness, e.g., deflection of the material beingworked outside of required tolerances, can be detected by determiningthat the image data is a broader spread than expected from a giventhickness of material.

It will be appreciated that dimensions of the workpiece may bedetermined or checked by the imaging system using software.

The portion of the beam that does not illuminate the tool or work pieceimpinges on an image forming plane in the form of a screen e.g., ashadow screen. An imaging device, such as a digital camera having one ormore pixel matrices is used to capture the shadow image created by thepattern of attenuated and un-attenuated light falling on the screen. Thecaptured image is processed to look for differences between a library ofstored image or images, or compared to an earlier calibration run wherethe tool, die and un-worked (or pre-worked) work-piece are imaged in afirst pass. An algorithm is used to determine from the captured image,and in comparison with stored data or a previous image, differencesbetween the most recent image and stored data or previous image tothereby determine the angle of bend applied to the material beingworked. The system can also detect whether or not the tool is thecorrect tool for a chosen operation by comparing the imaged tool with alibrary of tool profile data.

FIG. 4 shows an end view of a sheet of metal 3 a having been bent 3 b ina press brake. The angle of bend a (alpha) is determined by a line ofbest fit from the data derived from the pattern of the attenuated beamreceived by the pixel matrix. Errors in the tolerance of the thicknessof the material can be determined by the spread of data exceeding thethickness of the material e.g., beyond 3 mm for a 3 mm material. Whilstthe system may be used to determine whether the thickness of a materialfalls within or outside of expected tolerances, the system may also, oralternatively, determine distortion or variation of machining along afurther dimension of the work piece, e.g., bend in along a length ofsheet of material or distortion of milling or lathe work on a face of awork piece, falling within or outside of required tolerance(s). Thefurther dimension may extend perpendicular to the end on view of thework piece illuminated by the light source, such as the length of asheet of metal having a V section bend formed along a length thereofwith an end of the V section illuminated by the beam. For example, thesystem can determine whether a bend formed along a length of sheet metalby a press brake falls within expected tolerances, such that the imagingsystem can check for distortion, e.g., ripples or waves and the workpiece rejected or reworked, and/or the machine adjusted or repaired, ifdata is found to fall outside of required tolerances. Thus, the imagingsystem can “look along” a linear dimension of the material to checkwhether the machining operation e.g., bend imposed by a press brake onsheet metal, is within tolerances along that length of material.Preferably the resolution of the pixel matrix is 640×480 pixels, therebyallowing suitably precise measurements of the work piece and/or machineparts. It is envisaged that a “first pass” would be carried out in orderto image the tool and the die in the absence of the material to beworked, and thereafter a comparison can be made with the material inplace to look for differences between the initial “first pass” image andthe subsequent “worked” image. The comparison can be made by storing the“first pass” image in an initial block of memory whereby the imageprocessing means can compare the subsequent image or images with theinitial memory. In addition, the profile of the tool tip and/or the diecan be imaged in order to help avoid clashing of the working tool tipwith the die should an incorrect tool tip or die be chosen. The tooland/or die can be compared to a library of tools and dies and thereforechecked to ensure that the correct tool and/or die is selected for achosen working operation.

FIG. 5 shows multiple receiving sections of the receiver, eitherhorizontally disposed 1 a-d, vertically disposed 1 e-h, or a combinationof both. It will be appreciated that more or less multiple receivingsections may be used, and in varying patterns, e.g., they need not behorizontal and/or vertical sections. Due to relatively high speed of thetool during the safety mode i.e., prior to the mute point 5, thereceiver may be unable to process the large quantity of informationsufficiently quick if an entire receiver matrix or array used. Becauseof the large number of pixels in a completely active array, receivingall or a substantial proportion of the block laser beam during safetymode can result in an overload of information to be processed at highspeed during operation of the machine. Therefore the matrix or array canbe divided up into active receiving sections as shown. That is, sectionsof the receiver may not necessarily be utilised during safety mode butactivated during the imaging mode. Alternatively or in addition, theblock laser can be divided up into transmitting sections for receipt bythe receiver in safety mode. The full or substantial proportion of theblock laser can then be utilised during imaging mode. As each section ofthe beam approaches the mute point, the respective receiving section isdeactivated. When the last beam section reaches the mute point, orshortly before tool tip reaches the mute point, the system switches overto imaging mode and the safety mode is deactivated. The tool and/or workpiece are then imaged to determine the degree of work carried out on thework piece or that the tool is as specified.

FIG. 6 shows a perspective view of a particular embodiment of thepresent invention. A light source 26 and receiver 28 are shown inalignment with one another and mounted to a press 20 for travel in thedirection of movement of a working tool 22 of the press. Thus, the lightsource and receiver travel with the tool (vertically upwards anddownwards), with the light beam 30 from the light source being directedtowards the receiver. The light beam 30 is of broad 2-D or “block beam”cross section sufficient to illuminate a useful portion of an end of awork piece 32 in position on the die or anvil 24. The work piece isshown partly worked in already having a V section bend. In thisembodiment the remainder of the beam un-attenuated by the work pieceand/or tool is received directly by the receiver 28. The receiverincorporates a lens arrangement, as in a camera, to focus the overallsize of the captured image onto a CCD of a digital camera. The image isprocessed and can be output to a screen for viewing to check for obviouserrors in the work piece or tool alignment, and/or used to determinenumerical values to show correctness/errors in the work piece e.g., fordisplay by a monitor of a CNC press, and/or compared to a library ofexpected images. In addition or alternatively, image data can becompared and/or checked by software, which software may be incommunication with or incorporated into the processing means.

FIG. 7 shows a front view of the press 20, similar to that shown inFIGS. 6 and 8, with the light source 26 and receiver 28. In thisembodiment, the imaging mode light beam 30 illuminates an end of thework piece 32 and tool 22, such that the work piece and tool are imagedonto a screen 34 as shadows along with the remainder of the light beam.The receiver then determines the image from the shadow image created onthe screen 34. The degree of bend imposed on the work-piece, and/or theamount of distortion along the length or width of the work-piece, isthen determined e.g., by a line of best fit method comparing thecaptured image with an expected image. As depicted, the screen 34 ismounted to travel with, and form part of, the overall light beamreceiver 28. The screen may be moved out of the path of the light beam30 when the system is in safety mode and moved into the path of thelight beam for imaging mode.

FIG. 8 shows a cross section taken through line A-A of the system andmachine of FIG. 7. The broad 2-D cross section “block beam” beam 30 canbe seen with the tip of the tool 22 impinging into the beam. As the tooltravels downwards, the work piece 32 (and tool) will intersect the beam.When the tool travels upwards, the system can change over to a safetymode (preferably at the mute point, whereby incursion of an object intothe beam causes the machine to halt further movement.

FIG. 9 shows a broad (block) beam safety system and/or imaging system40. A transmitter 42 transmits a broad beam 44 which is received at ascreen 46, such as a shadow screen. It will be appreciated that thedrawing shows the full cross section of the beam falling on the screen.However, in use, a workpiece and/or tool may interpose at least in partbetween the transmitter and screen, thereby attenuating at least aportion of the beam falling on the tool/workpiece to create a shadowimage at the screen. The resultant screen image is imaged by multiplecameras 48 a, 48 b. At least one camera may be a CMOS camera, which mayhave a resolution sufficient to image a 60 mm×50 mm or 60 mm by 60 mmcross section beam. The camera(s) may be fixed focus cameras imagingfrom the screen.

The imaging system can be used to identify the tool tip, e.g., forcalibration of a commencement of a working stroke or cycle, such as atthe top of a downward stroke of a press brake. Such imaging can be usedto identify the position of the tool tip at the commencement of a strokeand therefore, where the position of the tool tip is known and thedistance needed to stop is known, the position, size and/or shape of theprotection zone can be determined.

The relatively large area of the block or multiple light sources can beprogressively muted e.g. muting the effect of rows of pixels, or groupof pixels, in the vertical plane the protection area as the tool (withthe protection area) approaches and goes through the mute point. Forexample, for a receiver including an array of pixels, an output signalfor successive rows of the pixels can be progressively muted as orimmediately before a corresponding portion passes through the mutepoint.

A second camera 48 a, such as a low speed high resolution camera, can beprovided. This can provide 1280×960 (or higher) pixel array images ofthe tool and workpiece.

An image processing module can be connected to the receiver circuit forcomparing tool images with information transferred from the CNC toollibrary. This verifies that the image of the workpiece is consistentwith the bend information and various angle checking functions (whichcan also be integrated into the press brake numerical control NC.

FIGS. 10a to 10d show successive stages during a progressive mutingphase. FIG. 10a shows the end of the tool tip 60 protected by aprotection zone 62. The tool tip and monitored zone travel downwardstowards a workpiece (not shown) on a die 64. A mute point 66 is definedto be a predetermined distance above the die and workpiece.

As the tool tip travels downward (see FIGS. 10b and 10c ), theprotection zone is progressively muted (hatched area) from the mutepoint 66 such that the leading portion 68 of the protection zone (inthis example the lowermost portion) becomes ineffective. This can beachieved by progressively muting or disregarding output signals fromsuccessive or staged rows of elements in a receiver (not shown). It willbe appreciated that the elements need not be deactivated, rather, theiroutputs may be disregarded for the purposes of a safety system but maystill be used for an imaging system. Thus, the beam may continue toilluminate the receiver (attenuated or not) and be utilised for imagingbut progressively muted for the purposes of a safety (halting) system.FIG. 10d shows the tool tip passing through the mute point. Thereforethe entire beam is muted due to the tool tip being so close to the mutepoint that protection is considered unnecessary or ineffectual (themachine being unable to stop within the remaining closing distance tothe workpiece.

The mute point can be a point established, a measured distance (sayapprox 2-3 mm), above the surface of the material to be worked, e.g.,bent. This provides benefits of:

-   -   1. Extra safety. Protection from when the bottom of the        protection zone touches the mute point all the way through to        when the last part of the zone mutes. This last line of        protection (as per basic diagram) can be after the tool tip is        entering the bottom die. This provides a substantial gain in        safety.    -   2. As particular rows of protection are muted, this can separate        signals to progressively slow down, and/or control the descent        of the top tool. Therefore the available protection under the        tool tip (as it reduces) can be matched to the speed (and        therefore stopping distances) the machine is allowed to travel        at.    -   3. Because the protection is being carried on down—as per point        1—the tool tip can be touching the material to be bent before        the tool needs to change to slow bending speed (typically 10        mm/sec). Therefore no safety speed (also 10 mm/sec) needs to be        activated before the tool arrives at the material. In previous        systems—such as single laser systems, when the protection is        muted the tool must be traveling at the required safe speed (10        mm/sec).        Points 2 and 3 recognise improvements in the cycle time of the        stroke and therefore more bends in less time, while also gaining        in safety.

The imaging system may be used to identify a profile of the workingtool, and the tool can be checked for correctness e.g., against alibrary of known tools. Also, the tool may be imaged to determine arequired mute point from the tip of the tool.

What is claimed is:
 1. A system comprising: at least one lighttransmitter, at least one corresponding light receiver including aplurality of receiver elements configured and arranged to receive lighttransmitted from said at least one light transmitter, a machineincluding first and second portions arranged for relative closingmovement during operation of the machine, and wherein the system isconfigured and arranged to restrict or halt further relative closingmovement of the first and second portions when the light transmitted toan operative proportion of said plurality of light receiver elements isinterrupted, and wherein a safety operation of selected ones of saidplurality of light receiver elements is progressively disregarded ormuted for an increasing number of the light receiver elements as thefirst and second portions of the machine close relative to one another.2. The system as claimed in claim 1, wherein the system progressivelydisregards or mutes the safety effect of signals from rows or groups ofsaid light receiver elements.
 3. The system as claimed in claim 1,wherein the at least one light receiver includes at least one array ofpixels providing said plurality of light receiver elements.
 4. Thesystem as claimed in claim 1, wherein the safety operation isdisregarded from a mute point for progressive numbers of the receiverelements as the first and second portions close relative to one another.5. The system as claimed in claim 1, wherein the light receiver includesa high resolution camera.
 6. The system as claimed in claim 5, whereinthe camera provides a pixel array used for imaging a workpiece to beworked by a tool of one of the first and second portions.
 7. A method ofoperating a combined safety and imaging system for an industrialmachine, said machine having first and second members arranged forrelative movement, the first member including a tool holding portion andthe second member including a workpiece holding portion, and saidmachine including at least one transmitter for transmitting at least onebeam of light to at least one receiver; the method including the stepsof: operating the system in a safety mode whereby interruption of atleast a portion of said at least one beam results in halting of saidrelative movement; and operating the system in an imaging mode whereinat least a portion of a tool and/or workpiece is imaged, or an extent ofwork carried out on said workpiece and/or a profile of the tool isdetermined.
 8. The method as claimed in claim 7, wherein the system isconfigured to act as an imaging device from a predetermined point orapproach distance relative to a workpiece.
 9. The method as claimed inclaim 7, including the step of switching the system from the safety modeto the imaging mode at a predetermined point or action.
 10. The methodas claimed in claim 8, wherein the predetermined point is a mute pointwhere the safety system becomes inactive from that point.
 11. The methodas claimed in claim 9, wherein the predetermined point is a mute pointwhere the safety system becomes inactive from that point.
 12. A methodof operating a safety system for an industrial machine, including thestep of progressively muting or disregarding the effect of portions of aprotection zone for a moving tool of the machine.
 13. A method asclaimed in claim 12, wherein the industrial machine is a press, and themethod includes progressively disregarding or muting a safety operationof rows or groups of receiver elements of a light receiver from apredetermined approach distance relative to a workpiece held by thepress.
 14. The system of claim 1, wherein the machine includes one ofthe following: a press brake, a bending machine, a forming machine, anindustrial press, a lathe, and a milling machine.
 15. The system ofclaim 1, wherein the machine is a press brake, the first portion is ananvil, and the second portion is a blade.
 16. The system of claim 1,wherein the first portion of the machine includes a tool-holding portionconfigured and arranged to hold a tool, the second portion of themachine includes a work-piece holding portion configured and arranged tohold a workpiece, and the machine is configured and arranged to engage atool held by the tool-holding portion with a workpiece held by thework-piece holding portion by moving the tool and workpiece relative toone another.
 17. The system of claim 1, wherein the system is configuredand arranged to mute ones of the light receiver elements to which lighttransmission is blocked by the first or second portions of the machineas the closing movement positions one or both of the first and secondportions in a path of the light transmission, and restrict or halt thefurther relative closing movement of the first and second portions inresponse to light transmitted to a portion of the light receiverelements being interrupted for other ones of the light receiver elementsthat are not muted.
 18. The method of claim 7, wherein the industrialmachine includes one of the following: a press brake, a bending machine,a forming machine, an industrial press, a lathe, and a milling machine.19. The method of claim 7, wherein the machine is a press brake, thefirst member is a blade, and the second member is an anvil, and whereinthe step of operating the system in the safety mode includes deformingthe workpiece by moving the blade toward the anvil and engaging theblade with the workpiece.
 20. The method of claim 7, wherein the firstmember of the machine includes a tool-holding portion configured andarranged to hold the tool, the second member of the machine includes aworkpiece holding portion configured and arranged to hold the workpiece,and the step of operating the system in the safety mode includesoperating the machine with the at least one transmitter and the at leastone transmitter to halt movement of the tool relative to the workpiecein response to interruption of the at least a portion of said at leastone beam.